6 34 THE LYMPHATICS. 



always superposed on the capillary blood-vessels, one is always certain of injecting them 

 only, in taking the precaution to penetrate the membrane as superficially as possible. If 

 the point of the canula enters too deeply, the mercury will pass into the veins, and the 

 operation will be unsuccessful, and must be commenced again. 



To study the branches and lymphatic trunks, it will suffice to inflate them from 

 their origin towards their termination. This procedure, properly conducted and it was 

 almost exclusively the only one adopted by the older anatomists gives the most satis- 

 factory results, and is even sufficient to demonstrate the texture of the glands. 



The latter do not require any particular precautions in their preparation. 



CHAPTER II. 



THE LYMPHATICS IN PARTICULAR. 



WE will commence with the examination of the thoracic duct and all 

 its Affluents, and terminate by studying the great lymphatic vein. 



In this description the glands and principal lymphatic vessels will be 

 only referred to, the disposition of the networks being already noticed 

 in speaking of the different organs, and they will be further mentioned 

 when speaking of the nervous system, the organs of sense, and those of 

 generation 



ARTICLE I. THE THORACIC DUCT. (Fig. 293, T T.) 



Preparation. Tie the jugulars and axillary veins near their termination, as well as 

 the anterior vena cava about the middle of its length ; expose the thoracic duct by 

 removing the ribs on the right side ; open that canal near the pillars of the diaphragm, 

 and throw into its interior two injections of tallow, one forward, the other backward 

 from the incision. The first injection will fill the canal and the venous reservoir which 

 is intersected between the ligatures applied to the above-named vessels ; the second, 

 although directed in opposition to the valves, overcomes the resistance offered by them, 

 and passes into Pecquet's cistern and the principal branches which open into that 

 confluent. Or we may select one of these branches in the abdominal cavity for example, 

 one of those which lie beside the colic arteries near their origin and inject the entire 

 thoracic duct from its origin to its termination. 



But this proceeding requires more practical ability than the first, in order to find 

 the vessel which is tc receive the canula ; and if the animal is very fat, it is im- 

 possible. 



The thoracic duct is the general confluent for all the lymphatics of the 

 body, with the exception of those which come from the right anterior limb 

 and the right moiety of the head, neck, and thorax, 



Extent. It extends beneath the vertebral column, from the first lumbar 

 vertebra to beyond the entrance to the thorax. 



Origin. Its origin is marked by a very irregular dilatation described as 

 the sublumbar reservoir, or cistern of Pecquet (receptaculum or cyster nachyli), 

 into which open the principal affluents of the canal. 



This reservoir is divided, internally, by lamellae into several incomplete 

 compartments, and may be more or less voluminous and circumscribed, and 

 present very variable forms. 



It is placed above the abdominal aorta and the posterior vena cava, at 

 the great mesenteric artery, or more frequently a little behind it. In the 

 Dog it is of an enormous size, oval in shape, and prolonged between the 

 pillars of the diaphragm into the thoracic cavity. 



Course. To this reservoir succeeds a tube whose calibre is very irregular, 

 and appears singularly slender when compared with the diameter of- the 



